Can a Swamp Cooler run all day?

Can you run a swamp cooler all day? How humid will your living space be? And is there a risk of the electronics blowing up?

Quick answer: Yes, you can run a swamp cooler all day. Swamp coolers do not add humidity to your room indefinitely, because they run at room temperature (and don’t boil the water like a kettle). Also, they run on very little electric power, so they don’t overheat. To maximize running time, lubricate the fan every year.

Before we check why you can run a swamp cooler all day, let’s first have a look at why you oftentimes think you can’t run an electric device as long as you wish:

Why HVAC companies set time limitations for devices that can run indefinitely

In my experience, electronics manufacturers, and especially HVAC manufacturers spread fear and uncertainty. User manuals tell you that things are dangerous and you should not run a device longer than X hours.

And not only air conditioning companies do that. I’ve seen it with heaters and even gaming consoles. Spreading uncertainty about a topic is a way for companies to protect themselves.

For example:

Imagine your swamp cooler catches on fire (don’t worry, it won’t).

You sue the swamp cooler company for the fire damage. But they respond with “Oh, you were running your swamp cooler for more than 2 hours continuously. We are not accountable since our user manual prohibits running the device for that long”.

The real problem, is, however, not the running time of the swamp cooler. Any quality swamp cooler can run indefinitely.

The problem is that some swamp cooler companies use very cheap parts to manufacture their swamp coolers.

And if something goes wrong, for example, the fan bearings break and the fan doesn’t blow anymore, or the electronics stop working, the company can blame any faults on your usage instead of taking accountability for their quality problems.

That’s why you see so many devices (not just swamp coolers) have running time limitations in their user manuals.

This is obviously a hoax and merely legal protection.

Let’s have a look at what really happens when you run a swamp cooler for a very long time:

Room humidity after long running time

A swamp cooler will never make your room too humid, no matter how long you run it. Here’s why:

There’s a big misconception many people have that the longer you run a swamp cooler, the more water evaporates and the more humid the air in your room becomes.

This is false!

A swamp cooler can’t evaporate water indefinitely since it does not add heat to the water.

Many people think of swamp coolers like a kettle boiling water. The longer the water boils, the more humid the air becomes. This is only possible because the stove forces the water in the kettle to evaporate through heat.

A swamp cooler merely blows air over wet sponges. If the air in your room is already humid, a swamp cooler can not add more humidity.

And if the air in your room is hot, it evaporates water. If it is cool, no water evaporates.

When you run a swamp cooler in a dry room, the humidity level rises until it reaches a certain temperature-dependent humidity threshold.

After the air reaches this humidity, a swamp cooler can not possibly make it more humid.

“A swamp cooler is basically self-regulating as to the amount of moisture it injects into the conditioned space.”

David Andersen from the inspection community

The maximum humidity threshold your room can reach depends on two factors, which are air pressure and temperature.

Pressure is roughly constant around the globe (except in high-altitude areas). The temperature, however, varies.

Your swamp cooler, therefore, self-adapts to the temperature. If it is hot, it evaporates a lot of water. If it is cold, it doesn’t.

A long swamp cooler running time has no effect on the humidity levels in your room. After your room’s humidity level reaches the maximum, your swamp cooler stops evaporating more water.

You can run your swamp cooler however long you like. It does not matter. Just make sure to vent your room thoroughly a couple of times a day to equalize indoor and outdoor humidity levels.

Can a swamp cooler overload the wall outlet?

For any device to overload your home’s electric circuit, it needs to draw more power than the electric circuit can handle.

In the US, a standard wall outlet supports a voltage of 110V. In Europe, a wall outlet provides 230V of power.

With a regular 15 Amps circuit breaker, this means, a wall outlet supports the following maximum power output:

RegionMaximum power (with 15 Amps circuit breaker)
US (110V outlet)1650 Watts
Europe (230V outlet)3450 Watts

( To calculate these values, I used this formula: Power = Voltage × Amperage )

By the way: 15 Amps circuit breakers are the smallest amperage circuit breakers. It could be that your home has stronger 20 Amps or higher circuit breakers installed. I am using 15 Amps for the calculations to account for the worst case.

As you can see in the table, any wall outlet supports 1650 Watts. European outlets support even more.

A large swamp cooler uses only 250W of power. That is only 15% of what your wall outlet can handle.

Most swamp coolers use even less power, e.g. 100W or 150W.

In theory, you can run up to 6 large swamp coolers simultaneously without overloading the circuit.

Electric circuitry does not overheat or break when it runs all day. A good example is your fridge. It runs 24/7 and draws more power than a swamp cooler does (up to 400W and more depending on size).

You can safely run your swamp cooler all day. At least if we only approach the question from this purely electrical perspective.

Let’s check it from the mechanical perspective:

Will your swamp cooler break if you run it for too long?

Does a swamp cooler wear down and break if it runs for too long? This depends on the quality of the moving parts inside your swamp cooler:

  • the pump
  • fan bearings

Moving parts always cause friction. And friction wears parts down over time. If you run your swamp cooler 24/7, at some point in time it will break, guaranteed.

swamp cooler fan

Let’s check how long your swamp cooler lasts if you run it continuously.

Ball bearings lifespan

The ball bearings of a typical fan last for 50,000 hours of continuous usage.

This means you can run your swamp cooler for

50,000 hours ÷ 24 hours per day ≈ 2083 days


That is about

2083 days ÷ 365 days a year ≈ 5 years 8 months and 2 weeks

After this, your bearings will break.

This is, of course, just an average value. Sometimes bearings last a lot longer than you’d ever expect (which is why some cars run 200,000 miles and more), while others break down much earlier.

Swamp cooler water pump lifespan

An electric water pump lasts 10 to 15 years (source). So, it is not the limiting factor of your swamp cooler’s lifespan.

However, I could not really find any source about the actual running time of water pumps. Any source online just states “10 to 15 years”, but I highly doubt that this is 10 to 15 years of continuous running time.

I bet it isn’t.

I’d estimate a pump to last for 5 years if it runs continuously. Does that sound similar to the lifespan of ball bearings, which is also 5 years?

That’s because the motor inside the pump runs on bearings. Bearings always do the heavy lifting and the most movement in mechanics, and thus they are the parts that break down.

But, because that’s the case, and we humans need bearings so much, most bearings, even in cheap devices are of good quality.

Manufacturers perfected the art of bearing production. 5 years of continuous running time is impressive.

How to make your swamp cooler last longer

Now that we know that the only moving parts that can break in a swamp cooler are bearings, we can improve their lifespan:

“To reduce friction and minimize overheating, fans need lubrication.”

The simplest way to do that is to lubricate any moving parts once or twice a year. Lubricate the fan and, if accessible, the pump.

You don’t have to use a special lubricant. Just use bike lubricant or WD-40 or whatever.

Also, rinse and clean the sponge occasionally. This not only removes the smell, but also reduces the sponge’s airflow resistance.

If your sponge is clean, your fan does not have to exert as much force to pass air through it.

Although this is a small effect, it will add up when you run your swamp cooler all day.

Will a swamp cooler overheat?

A swamp cooler will not overheat. Swamp coolers use way too little power to cause anything to melt or become overly hot.

And even if that was the case, the water in your swamp cooler would absorb the heat and evaporate it.

So, it is almost impossible for a swamp cooler to overheat, no matter how long you run it for.

How much does running a swamp cooler all day cost?

Assuming an average electricity cost of 23 cents per Kilowatt-hour:

Swamp cooler sizeCost for running 24 hours

As you can see, swamp coolers are very affordable to run all day.

For comparison, a typical air conditioner consumes 800W of power which would be $4.41 per 24 hours.

Running a swamp cooler overnight

The biggest downside of using an evaporative cooler all day (and night), is the noise.

Swamp coolers make a lot of noise.

They are comparable to strong fans.

Even if their sales page advertises low noise levels, they are still noisy.

You can’t silently force air through tiny holes in a sponge. There just has to be noise.

At night, swamp cooler noise is very annoying.

So, either turn your swamp cooler off at night or, if you really need it, use earplugs for sleep.


You can run a swamp cooler all day. It does not make your room overly humid because it can not add humidity to your room indefinitely.

A swamp cooler can theoretically run continuously for years. It does not overheat and does not have any parts that easily break down.

So, run your swamp cooler however long you like!